Method and apparatus for producing hollow articles of rubbery materials



Sept. 20, 1949. w. L. JENKINS v 2,482,418

METHOD AND APPARATUS FOR PRODUCING HOLLOW ARTICLES OF RUBBERY MATERIALSFiled Aug. 6, 1946 2 Sheets-Sheet l Sept. 20, 1949. w. L. .JENKINS IMETHOD AND APPARATUS FOR PROD UCING HOLLOW ARTICLES OF RUBBERY MATERIALSFiled Aug. 6, 1946 2 Sheets-Sheet 2 Patented Sept. 20, 1949 METHOD ANDAPPARATUS FOR PRODUOING HOLLOW ARTICLES or RUBBERY MATE- RIALS WilliamL. Jenkins, Akron,

Ohio, assignor to The B. F. Goodrich Company, New York, N. Y., acorporation of New York v VApplication August 6, 1946, Serial No.688,593

This invention relates to the production of articles from aqueousdispersions of rubber and other rubber-like materials. Morespecifically, the invention relates to improved methods and apparatusfor the drying and vulcanization of deposits of latex rubber or depositsof other rubbery materials produced from aqueous dispersions thereof.

It has been proposed, heretofore, to vulcanize products shaped fromsolid rubber by the application of a high-frequency electrostaticfield.` This method of vulcanization, however, has not found applicationin the commercial production of dppedrubber goods, which usually havecomplex' shapes and configurations, for difficulties have been incurreddue in partjat least, to the inherent nature of latex deposits and inpart to the straight-line characteristics of an electrostatic eld Whichcauses curved areas of a deposit not disposed normal to the direction ofthe field to be heated less strongly than'areas normal to the field.

Therefore the present invention aims to provide simple, economical andefficient methods and apparatus utilizing a high-frequency electrostaticeld for the drying and vulcanization of' shaped hollow rubber goodsproduced from latex or other aqueous dispersions of rubber-likematerials.

The invention also aims to provide methods and apparatus which willspeed the drying and vulcanization of fresh latex deposits so as to makepossible the production vof hollow rubber articles of non-uniformsection in a continuous manner.

I have found that a deposit of latex rubber or other rubber-likematerial may be vulcanized in place upon a supporting body or formadapted to function as an electrode Within the deposit to apply ahigh-frequency alternating electrostatic field of substantially uniformcharacteristics to the deposit so as to incite therewithin a maximumdegree of reaction to the field. I have-also found that a Wet, freshlyformed deposit of latex rubber or other rubber-like material producedfrom aqueous dispersions thereof may be dried by a few minutes exposureto a high frequency alternating electrostatic field applied to thesurface substantially throughout its extent. I have further found thatthe best method of attaining uniform and eflcient drying andvulcanization of latex coagulum deposits through the application of auniform electrostatic field is by depositing, or otherwise associating adeposit of rubbery material with a shaped supporting or forming mem;ber, the forming portion of which comprises a body ofelectro-conductivematerial disposed interiorly thereof and uniformly with respect to theOutside surface of the forming member so that an effective electricalsuface of such electroconductive material is presented to the entireinner surface of the deposit, and by associating or surrounding thedeposit-covered forming member, preferably while said deposit is in theundried condition, Y with a second body of electro-conductive materialdisposed about the deposit in a manner to bring the effective electricalsurface of such second body of electro-conductive material in uniformjuxtaposition to the outside surface of the deposit. Thus, the twobodies of.electrocon ductive material are separated by Va gap uniform inWidth but of irregular configuration so as to conform to the outlines ofthe deposit and to form the plates of a condenser in which the wetdeposit is included as the material to be dried and vulcanized.

I have found that a preferred method lof producing irregularly shapedrubber articles or articles having a generally non-uniform section, suchas rubber gloves, consists in producing the latex coagulum deposit uponforms of a glazed impervious porcelain material or the like for suchform-material imparts ,a smooth inner surface to such deposits but,unfortunately, is non-conductive in character. In order to render suchglove forms capable of functioningproperly as an electrode, it ispreferred to design the forms so as to possess a cavity with a uniformWall thickness so that the inside surface of the cavity will closelyconform to the configuration of the outside surface. The cavity may thenbe filled with an electro-conductive material such as a fluid materialwhich will flow into and assume the shape of the cavity, thus locatingthe eifective electrical face of such electro-conductive material at theinterface between the dielectric porcelain material and the fluidelectro-conductive material. Among the fluid electro-conductivematerials which may be used are aqueous solutions of electrolytes, lowmelting molten metals or alloys, such as molten Woods metal, moltensaltsY or mixtures of salts, and the like. The forming'and supportingmember may also comprise a hollow form of glazed porcelain materialsimilar to that described above but reinforced with a metal liner orcore which serves as the electrode and which is fitted closely withinthe cavity so as to bring the effective' electrode face at themetal-porcelain interface. An al1-metal forming member, preferably ofaluminum or other highly conductive material, may be used with advantagewhen a smooth polished surface is not essential on the inside surface ofthe deposit.

I have found that the outside electrode may be located so as to producethe electrostatic field substantially normal to the surface of thedeposit throughout its extent by immersing the depositcovered .formcontaining the inner electrode in a bath of fluid electro-conductivematerial such as a bath of a molten low-melting salt, a bath of moltenWoods metal, or an agitated bath of high boiling organic liquidcontaining'thereinsuspended particles of electro-conductive mater'i'alsuch as graphite. If it is not desired to dry the deposit before orduring vulcanization, .the apparatus may embody an outerelectrode'comprisingzazbath f of water containing an electrolyte such assulfurie acid, sodium chloride, or .the like. I-t is preferred, however,to employ as the outerelectrode a noneaqueous or anhydrous liquidelectro-conductive material. The'outer electrode may also .comprise asurrounding metal formera sizefand ,shape vto per-mit :its being iittedv.closely .about configurations of the .form-and deposit.

In 'the :production Voi hollow :dipped rubber goods .from aqueousdispersione of rubber-like material by the :methods -of Vthe prior Aart,the drying step often lhas .consumed as muchas 8 hours fora deposit ofy0.016 inch thickness, and, of course, vmuch greater :drying rtimes are.Vrequi-red .for thicker deposits. The `vulcanization step isalsotime-consuming as may be seen from the :fact that vulcanization:in-steam, hot'air, or hot water commonly takes -one hour or more attemperatures-of 2501-F. ormore. Thus, it can be seen that-the drying andvulcan-ization steps. .con- .sume sufficient time to conne theproduction of dipped lrubber goods to a. stepwise-method. With the:methods andapparatus outlined herein .the speed of production may beincreased sothata continuous process Ais feasible .from .which greatsavingsin time, .labor and `cost of equipmentare realized as wellas .asigni'cant improvem'entin .product quality.

invention will v.be .described with further reference to .severalspecific embodiments .as .shown in the accompanying drawings, of which:

'1 is a plan View of4 an apparatus or'the con.- tinuous productionofsurgeons gloves .or house- .hold-.typerubbergloves, the view showing achain actuated glove 'form conveyor along which are disposed, asindicated b y legends, stations lfor dipping, `washing, y.preliminarydrying, bead rolling, 'inal drying and vulcanization, Vand stripping.

.Fig.'2 is an enlarged .sectional view taken along the linel'2-2 of'Fig.l1 showing a number of `dipping 'forms at `the stripping station `one ofthe `forms having thereover aiinished glove deposit ready for stripping.

'Fig 3 is an enlarged sectional View takenalong the 'line 3-3 of Fig. 1.

Fig 4is an'enlarged sectional-viewtaken alongr the "line 4 4 of Fig. 1.

Fig. 5 is an enlarged elevational viewwith portions-broken away and insection-showingya meta-l vforming member or gloVe-shapedfelectrode'whichmay `be used in conjunction V.with the f'apparatus of'Fig. 1 toformand.vulcanizefglove-shapeddeposits of Yrubbery materials.

.'Fig. 6 is an enlarged,elevationalwiew with-,pob tions-broken away andin sectionshowinganother embodimentof -a forming member whichfmaybe.used in conjunction with-the apparatusof Fig. f1 toproduce rubber.gloves and 'ha-ving rportions brokeniaway and in section to show theglazed porcelain Amaterial of -the outer portion of -ithe 4 form andshowing in dotted lines the extent of the cavity therein in which theelectro-conductive fluid material of the inner electrode may bedisposed.

Fig. 7 is an enlarged elevational view similar to Figs. 5 and .6showinga third illustrative forming member with portionsvpartiallybroken away and in section to disclose the glazed porcelain Amaterial ofthe outer portion of the form and a glove-like metal liner or corewithin the otherwise-cavitied lporclain form to serve as an innerelectrode.

Fig. 8 is an elevational view of a second embodimentfof'apparatus iforthe production of vulcan- :ize'd rubbers' 'deposits showing a glove-likeform- Ling member 'tas iniFigs. 5, 6 and 7) surrounded with ametal wiregrid outer electrode.

Fig. '9is a sectional view taken along the line B-9f1orfFig- 8.

Referring to the drawings, Figs. 1 to 4 show a .preferred iorm y.ofapparatus 4for the -continuous production ofhollow .rubber articlessuchas.-rub ber gloves. The apparatus comprises ralcontinuous channel rail.track .IU .hung Aon .three .cross plates Ifl, .ll bolted .to the-topsof three .center support posts |'2, .I'2 .and .supported :on .two endsupport posts i3, .I3 .bymeansof .brackets I4, .i4 and top plates l5,l5. The top plates l5., 4I5 have projections la,A .15a .whichextendoutward vand downward so that .the channel rail Il! .may .be secured.theretolas by .stud .bolts .16, L6. .The .two endsupport posts 1.3, lf3.each havevertical nonrotating shafts l.-`l, l.1..supported.therein onthrust collars .|3, I8 and secured against .vertical movement -.by locknuts .'13, 4B. 'I-he non-.rotating shafts 1.1, .ifi :are iitted withinv.ireely rotatable sleevesZ, 2U whicharein .turn supported on .ballthrust bearings 21, .-2'1. vSprocket Vwheels 22, .22 aresecured to.thesleeves-Z, 20 by meansfofkeys 23, L23. The sprocket .wheelsA 22.,.22,rotate .in ,a s1ot...24,in the `charmel railfw so l.that-a conveyorchain 25 traveling over the sprocket wheel-s will bev carried .within:.thechannelail rI 0. The chain 25 .carries a .plurality .of form hanger.brackets 26 .disposed between the .connecting .links .of .the Ychain2.5; vthe brackets 25, .2.6 `traveling:along within the 1 channel IrailLil and .being Isupported against the .vertical .sides .21, .2l ofthe'C-shaped cross section of thechannelrailbytravelingsguide wheels.28, .28. on. thehanger .brackets-2 6., .26. The conveyor chain .25.. isadvanced around .the channel rail L0 Vby-a worm gear.driVe29,-thefgear29.a of vthe-wormfgear .drive zaloeing .secured tothesleeve 20 by. means of .the keyl 23.

The .hanger :brackets 25, .26 have holes 30, "38 atthe `outer-.edge ofthe. .bracket Afrom-which Vare hung `form yholderfa-rins :3l whichrotatably supportiy dipping; (ar-forming. members '32 32. The forming.mem-bers lor -dipping forms 32, 32 are journalledinlthe, `form holders3I-,,3I Vori-shafts 133,-.33 which .are provided at -the bottom .-withthrust collars 34, ySil 1and at y.the .to p with 1friction drivewheels-.35, 35 .whicharepinned to the shafts 33,133fby,-pins.36,135andirotate-inopenings .31, `3J in the yform .holder :arms lil, .3L TheVfriction drivelwheels ,35, 35fmake -contactwitha succession of curvedraise and lower vguide bars-whichare disposed below .thel-channelirailI0, ;in a manner to lift the forms 32,v leutandsidewards substantiallyto-the horizontal position inv order to raise the forms/over `the edges ofla, succession@ of tanks in A the. course f of their -travel around .thechannel rail.` 0.

Thefdipping .form i32 bar A0 over theedge srst .raised byv thefguide.offa tank 4|- containing .a

solution of aform lubricant, the form 32 hanging inthe vertical positionduring theshort distance oftravel in the'tank. Theform 32 then is raisedoverthe other .Wall of tank 4I. by a second guide bar 42 and loweredinto a tank 43 of ag coagulant for aqueous dispersions. Similarly, theguide bar raises theA form 32 andv lowers'it into a third tank.45of;latexV or otheraqueous dispersion of rubbery material. After a periodof travel in the lat'eX tank 45 (the break in the apparatus indicated inthe latex tank of Fig. 1 is to indicatevthat the latex tank 45 may bemade of proper length to conform to the requirements of the type of'latexv composition being used and particularly to provide the requiredtime of immersion to produce the thickness of deposit desired). Theguide `bar 46 raises the forrn 32 out of tank 45 and dueto theteeth-like corrugations 46a, 43a in the barl 46 the form 32 will beshaken and vibrated in order to break the film of latex which frequentlybridges the gap between the fingers of Adipping formswhen they are beinglifted from latex. After being lowered to the vertical position by theguide bar 46 the form 32 passes'be- :tween the constricted sides of washtank 41 which iS prOvided with two batteries of Water nozzles or sprays48, 48 which wash the latex deposits adhering to the form 32 to removethe small quantity of ,uncoagulated latex or dispersion thereon and toeffect further "setting of the deposit. As the form32 passes between theconstricted sides of the Wash tank 41 the friction drive wheel 35 makescontact with .a guiding bracket 49 so that .the form 32 is rotatedbetween the nozzles 48, 48. It is. to be noted that the wash tank 41 inFig. 1 is b roken to indicate that the length of the Wash tank willdepend on the characteristics of the latex composition being used. v

. From the Wash tank 41 the form 32; Still hanging in theverticalvposition, enters a hot-air oven 50 for a preliminary dryingperiod during which the surfaceV moisture is removed from the latexdeposit andthe surface of the rubbery material is renderedslightly'tackyso that a bead may be rolled at the Awrist portion of -the glove..` Fromthe air oven 50, the form, still hanging in the vertical position,enters a bead-rolling station where an elongated driven brush 5l rotatesagainst the wrist portion of the form 32, as shown more clearly ,in Fig.4, so as to press the form 32 against a guide bar 52 supported at thebottom of the channel rail l by a bracket 53. The guide bar 52y shouldpreferably be insulated from the channel rail l0 by a strip ofinsulating material 54 such as asbestos board, Bakelite, hard rubber andthe like for reasons which will later appear. The brush l is inclinedlongitudinally so as to gather lal b ead androll it down the form adistance equal to the difference in height between the two ends of thebrush 5I. As the brush 5I presses against the form 32, the frictiondrive Wheel is rotated vagainst guide bar 52 so that the form is rotatedcausing a continuous bead to be rolled on the glove deposit around thecircumference of the Wrist portion of the form, Rotation of the brush 5Iis effected by a pulley 55 on one end of the brush 5|,.the pulley beingdriven by a V-belt 56 driving from any convenient source of motive power(not shown). e Y After leaving the bead-rolling brush, the form 32 islifted by the guider bar 52 over the edge of a vulcanizer .tank 6| whichis filled with an electroconductive fluid material. The form 32 travelssubstantially the full length of the tank 6l hang- ,ingfin asubstantially vertical position with the friction drive wheel 35restinglagainst a bus bar 62 which is connected to a s ourceof high-frequencyalternating current (not shown).l The bus bar 62 is supported from thechannel rail l0 by a bracket 63 Whichis insulated from the electried busbar or guide bar 62 by a strip 64 of insulating material such as hardrubber; asbestos board.' Bakelite, or other suitable material. The tank6| is connected to the other terminalof the same source ofhigh-frequency current as the bus bar 62 so as to conduct the highfrequency current to the electro-,conductive material therein.

The high-frequency alternating current circuit is rcompleted from theelectrified bus 'bar 62 through the friction drive Wheel 35, thencethrough the form supportshafts 33 to the form itself and then throughthe latex deposit to the fluid material in the tank 6|. The form 2isinsulated from the form hanger bracket'26 land from. the rest of theapparatus since theuform holder arms 3l, 3l are made of insulating material such as wood, molded Bakelitaumolded asbestos composition or moldedhard vrubbery or others.

The form 32 is lifted from the vulcanizer tank 6l by a curved guide bar65 and the gloves may then be talced on the outside and stripped fromthe form either by hand or .by a mechanical stripping machine disposedalong the conveyor after the vulcanizer tank 6 l Y The drawings disclose.a number of embodiments of dipping and supporting forms which may beused interchangeably on the conveyor apparatus described above. Fig. 5`shows an Vallmetal form 32 which is semi-hollow (for reducing theweight) and havingsolid metal finger.` sections. The form is provided atthetop with a cover 10 having a vent hole 1 I, the cover 10 beingsecured within the flared top rim of therform by a pin 12 passingthrough the rim of the form, through the cover 10 and throughthevform'support shaft 33. This particular type` yof forrnis preferablymade of aluminum because of itslightness and because aluminum isrelativelyvinert with respectv to its effects on rubber. vHowever,

steel andA other metals,v may also be used as a material of constructionin makingall-metal forms. Y l

Fig. 6 discloses an impervious, glazed porcelain form which is -hollow aconsiderable distance into the linger sections. This form may be filledwith an electro-conductive material either lfluid or solid in naturewhich material may beY inducedto substantially fill the cavity of theform so as to be in intimate contact with the inside surface of theform. The all-porcelain form 32 is provided with an integral rim uponwhich Vth-e cover 8| may be seated with a sealing gasket 82 interposedtherebetween. The cover r8| is secured to the rim 80 by a crimpedferrule 83 which is further secured to the rim 80 by a pin 84 passingthrough the ferrule 83, cover 8| and hanger shaft 33. Since the cavityof the form 32 is to be lled with a fluid or other electro-conductivematerial, the cover 8l is provided with a vent hole 85. To preventescape of fluid from the form 32 when itis lifted to the near horizontalposition in passing `from one tank to another, the vent hole 85 isprovided with a spring loaded ball check valve 86 or similar device. Inorder that electrical contact be made with the fluid contained in theform cavity, the hanger shaft 33 is provided with an extension 81extending cavity.

discloses a further modification .of Vdipdown into the form 'trifi-'edWalls of the tank.

*etrangere 7. pingI form whichmayf beL usedVv in'y conjunction with theglove-making apparatus ofFig. 1, the form having a glazed, imperviousporcelain outer shellSll`7 and a Ametal core 91 inside the porcelain,the metall core9'l extending down part way into thel nger' portions. A;ventedi cover 92? is 'tted withinv a flared rim portion- Slof themetalcore 915 and securedby means of a piny 94- passing through the'rim: 93,the cover 92 andi the hanger shaft 33..

Intheapparatus of Fi'g. 1 the drying and vul"- canizing station'- may`be modied' by' omitting thelelectro-conductive fluid material andpassing the; rotating electried forms between' the elec- (It would bepreferable in this case if the walls were' placed' closer togetherfor'this purposethanthey appear inthe drawings)Y Another modificationofthe drying and vulcanizing ftankisshown in Fig. 8. The forms 32, 32moving into-the drying andfvulcanizing station may ber surrounded with awire grid' outer electrode [(50, the grid being of abasketelike-cylindrical shapesimilar to the form so as to impress afield substantially normal to the deposit; Anyofthe glo-ve forms shownin the accompanying drawings may be used with the wire grid outerelectrode ofV Fig; 8. (The form shown in the sectional view of Fig. 9being the form shown in Fig. 7^' having a porcelain outer shell 90 andan inner metalliner 911.)

In operation of the apparatus oi Fig. 1 the conveyor system advances theforms 32'through a succession of dipping steps through the vulcanizationstation `to the'talcingV and stripping stations. timesuicient to wet theform in a tank 4l* containing aA dispersion in a volatile solvent of aform lubricant such as talc-or soapstone in valcohol' or acetone,- theform drying very quickly While it is being advanced to the next station'where itis immersed inftank 43` containing a volatile solution of acoagulant for aqueous disfpersions of rubbery materials; coagulant'ssuchas anyof the salts of the'polyvalent metals such as calcium nitratedissolved in alcohol and ace- :tone oracetic` acid or othersmay be used.The form again drieswhile itis being advancedto the tank 45 containingrubber latex or other aqueous: dispersions 'off rubbery` materials. The

timeof' immersioninY latex willv var-y according ktio-the thickness ofdeposit desired and the'com position of the co'agulantE solutionl It hasbeen found that; anv immersion time eff onei andi one'- ha`l`fminuteslwillI produce a coherentdeposita `of"neoprene= (pol'ychloroprene) oi"substantiallTy` uniform thickness throughoutv (approximately O10'12ftoOlUlGlinch in thickness when dried). The depositcovered forms then enterthe `washing tank where water sprays 48, E8' remove vnoncoagulatedilatexfrom the outside surface ofi the deposit andthe residual` coagulantfrom; exposed areas'off the forming member in order to'preventvdeterioration of the rubber and to minimize danger of arcing ofthe'high-frequency current `in the subsequent electronicvulcanizationstep. YFromA the washing stationI the forms move to anairoven-'Sl for Va preliminary drying at'` fdd-250-u F. toremove surfacemoistureand to render the surface slightly tacky in' order to facilitatethe subsequent bead-rolling step.

From the-airoven, the'forms passfbetween the rotating brush 5|? ofthebead-rolling'machine andi the guide bar 5'2?, the` forms rotatingllso as to form a continuous bead around the wrist portionofftheglbveiforma From the befahl-rollingV station The forms are firstimmersed for a the. effects tablishingy a1 high-frequency electrostaticfield Vgenerally 'normali tothe deposit on the' form.

Uponexposure Ato the high-frequency current. the deposit ofvcoagulumis-atrst. so highly conduce tive (due to the presence ofcoagulant diffused through the water phase of the coaguluml'thatacurrent Vows through the coagulum. 'llhey flow of currentrissuflicientto'result in considerable resistance heating. After thedeposit vhas-been heated by.-v resistance to the current flowv an'dby ofthe electrostatic Vheld the Water is driven from the deposit intotheelectroecondu'c'- tive fluid inthe vulcanizer tank, which will usuallybe at a temperature above thek boiling.` point of'r water so as to'.vaporize the moisture driven from the-deposit and' drive it oi into'theatmospher-e as'steam.

Underthe usual operating conditions thedeposit must be he'atedto atleast-180th "2121F.' in order'to speedily expel the water.' Untilthe'de'- positl i'ssubstantially-dry Vits temperature will not risesubstantially above 212 F., but whendry, the temperature ofthe depositwill rise to 250 to 300 F. or more at' which temperaturesa':deposit-fromthe usual' latex compositionsI may be speedily vulcanized sinceV theelectrostatic- 'eldy has an accelerating eiect on thevulcanizationreaction. Atthe start4 of the dry-ing cycle the Vvoltageacross thedeposit will be low `duey toy the heavycurrent induced in the-circuit bythe high conductanceof the wet deposit. When the deposit issubstantially dry the voltage rises and the* current ilow is reduced.The drying stagehas been found to take from 3 or 5to 10 or 15 minutesformore, depending onv the power input, the thickness andV size ofthedeposit, andits 'Water' content.

During the nal stage ofthe exposure of the deposit to theefectsof'thehigh-frequencyfelec; trostat-ic' held, vulcanizationV of the drieddeposit takes place. In this latter stage care should'be taken to adjustthe power inputso las to keep-the temperature of the driedl depositpreferably at from 250 to 325 F. for if the temperature risessubstantially above 325 F. the rubber isapt to burn; and blow orbecornespongyand cellular inA nature. In contrastY with the drying ofthe deposit, :the vulcanization of the `deposit will be complete in fromone to'three-minu-tes or slightly morel (depending on the power input,the type-of -1 chemical vulcanizationA accelerator employed in thelatexv composition, and the quantity of electronica-lly activecompounding ingredients, such as carbon black and metallic oxidespresent in the latex compositiom' Themethod hereinabove outlinedproduces a smooththin glove of a strength' `asA high as or higher thanthe best gloves produced by conventional'air, steam or hot w-aterdryingand vulcanization methods. For instance, a glove produced bythe-method-of this invention from aV latex of neoprene (apolychloroprene type of synthetic rubber) with a thickness of 0.012 to0.016 inches will exhibit a tensile strength'of 3000 to 3100 p. s. 1. Aglove produced from the same'latex by conventional methods usuallyexhibits a tensile strength of 2900 to 3000 p. s. i.

The method of this invention produces gloves much more chea-ply andefficiently than pre viously `known methods and :there are realizedgreat savings in` time 'and labor' as Well'- `as -a great saving infloorspaceby the elimination of conventi-onal air ovens and the bulkyracks and trucks usually needed forlthe many hand-operations involved inprior methods and apparatus.

Rubber. lor other. rubber-like' materials 4which may be used in themanufacture of -gloves or other hollow dipped rubber goods by the methodofv this invention include aqueous dispersi-ons of natural rubbers suchashevea, balata, and others, and synthetic rubbers andreclaimed rubbers.The synthetic rubbers whichA may benused include,without being limitedto', polymers of the 'conjugated diene hydrocarbonshsuch asbutadiene-1,3 and its homo-logs, with such copolymerizable monomericmaterials as styrene, acrylonitrile, methyl acryla'te, methylmethacrylate and others, and polymers of 2chlorobutadiene-1,3 eitheralone or with monomeric materials copolymerizable therewith. The aqueousEdispersions may either be naturally occurring or artificially preparedby any of the known methods.

Any appropriate source of high-frequency oscillating or alternatingcurrents may be employed and the frequency of the current may varywidely as is understood in the art. Generally, however, the frequencywill be greater than about one million cycles per second (one megacycle):and may be 1as high as a hundred, two hundred or three hundred millioncycles per second (100, 200 or 300 megacycles) or more. Voltages, powerinput, and the like also will be varied and controlled in the usual way,the details of which are well understood and form no part of the presentinvention.'

While the invention has beendescribed with particular reference tocertain preferred embodiments thereof, it is possible to make variationsand modifications therein without departing from ithe spirit and scopeof the invention as defined in the appended claims.

I claim:

1. In the manufacture of shaped hollow articles of rubber-likematerials, the method which comprises associating a shaped hollowdeposit of coherent coagulum comprising rubber-like material having anaqueous phase with a water-impervious hollow non-conductive supportingbody of irregular shape having electro-conductive material disposedinteriorly of said body in a position that the electro-conductivematerial presents a surface substantially conforming to the outlines ofsaid supporting body throughout iits extent, immer-sing the said bodyand deposit thereon in a bath of uid non-aqueous electroconductivematerial, said fluid material being in direct contact with said deposit,Iapplying a highfrequency alternating current to sai-d body and bath aselectrodes until the deposit has been dried and vulcanized to asubstantial extent, and

thereafter removing the deposit from the said body.

2. The method of manufacturing latex dipped articles which comprisesprogressively moving through a series of lstations a plurality of formsof water-impervious dielectric material, each being of irregular shapeand having a hollow interior conforming generally to the exterior shapethereof so that the wall thickness of said forms is substantiallyuniform throughout its extent and, in the course of the progressivemovement, depositing latex coagulum on 'one surface of each of saidforms in succession .by a ldipping operation, successively immersingsaid forms and deposits of coagulum in a bath of non-aqueouselectro-conductive liquid, disposing an electro-oon.-

electrode comprising anelectro-conductive liquid,

disposing a secondelectrode on the opposite side of said coagulum fromsaid liquidsaid second eleotrodehaving asurface substantiallycoextensive with said'coagulum but separated therefrom by said form,:and establishing an alternating electrostatic eld having a frequency ofat least one megacycle between said electrodes to vulcanize saidcoagulum.

4. The method of making an irregularly shaped hollow :article ofrubber-like material which comprises depositing a coagulum comprising avulcanizable rubber-like material upon the outer surf-ace of a suitablyshaped hollow glazed porcelain form, immersing the coagulum-coatedsurface of said form in an electrode comprising a body of 'anhydrouselectro-conductive liquid material, disposing a second electrode 'withinsaid form, said second electrode having a surface substantiallycoextensive with said coagulum but separated therefrom by the wall ofsaid form, and establishing 'an alternating electrostatic field having afrequency greater than one megacycle between said electrodes to dry andvulcanize said coagulum.

5. In the manufacture of irregularly shaped hollow articles ofrubber-like material, the steps which comprise providing a suitablyshaped water-impervious form of non-conductive material, said form beinghollowed out to provide an interior surface substantially conforming tothe shape of the exterior surface thereof throughout its extent andhaving an electro-conductive material disposed adjacent said interiorsurface to provide an internal electrode, depositing a layer ofwater-containing coagulum comprising rubberlike material upon theexterior surface of said form, disposing said coagulum-coated exteriorsurface in contact with a body of non-aqueous electro-conductive liquidmaterial, and establishing an alternating electrostatic field having afrequency greater than one megacycle between said internal electrode andsaid body of liquid toV dry said layer of coagulum.

6.Y In an apparatus for the manufacture of latex dipped goods bydeposition of a layer of wet coagulum comprising vulcanizablerubber-like material upon the surface of a hollow glazed porcelain form,heating means for drying and vulcanizing said layer of coagulum on saidform comprising a body of non-aqueous electro-conductive liquid materialadapted to serve as an external electrode, a body of electro-conductivematerial within said hollow form adapted to serve as an internalelectrode, said internal electrode being uniformly disposed with respectto the outer surface of said form, and means for establishing analternating electrostatic field having a frequency greater than onemegacycle between said electrodes to dry and vulcanize said layer ofcoagulum upon said form.

7. Apparatus for the manufacture of latex dipped goods of irregularconfiguration comprising a body .of non-aqueous electro-conductive 5111liquid material adapted 'to .serve as .an external electrode, ansuitablyshaped hollow-glazed porce- -lain Aform ,adapted .to A.support a fresh`deposit of vlatex `coawgulum -V-comprising vulcanizable rubberlike,material upon `its .outervsurfaca said .form havingan interiorksurface. substantially conforming ,to .t'heishape kof `thelexteriorlsurface thereof throughout `its extent, t a Jeoy .of.electro-nonductive/*material Vdisposed iadjacentsad interiorsurface.and .coextensive .therewith adapted Ltoserve as an internal electrode,means .for `immersing saidxcoagulum-coalted form in said external.electrode, :andmeansior iestalldlilimgv an .alternating :electrostaticrield having a vlrfequency greater than none .megaoyle o' between saidelectrodes.

WILLIAMLKVJENKINS.

' fGImED ,The following references are Vcf recor in the file of v'this.patenti STATES PATENTS Number Name .Date

[2,'0212299 Gammeter Nov. 19,1935 "2,U4l j78`8 ,Spr'unger "May 26, `1936"1261347 .'Dufour et al. 'NOV. "4, T941 "2;2981037 Crandell IOc't. 6,1&42 Y23299;2'69 Gammeter Octl 20, 1942 $333,143 Bennett L'NOV. A2,21943 '21395;920 'Grotenhuis 'Mar 15, 1946 Certificate of CorrectionPatent No. 2,482,418 September 20, 1949 WILLIAM L. JENKINS It is herebycertified that errors appear in the printed specification of the abovenumbered patent requiring correction as follows:

Column 10, line 3, after the word liquids strike out the commal andinsert the same in line 4, after coagulum; column 12, list of referencescited, after line 14,

insert the following:

FOREIGN PATENTS Number Country Date 477,911 Great Britain Jan. 10, 1938and that the seid Letters Patent should be read with these correctionstherein that the same may conform to the record of the case in thePatent Office.

Signed and sealed this 11th day of July, A. D. 1950.

THOMAS F. MURPHY,

Assistant Uommzaszonet of Patenftt.

